Everything comes to an end
“Everything comes to an end” — yes definitely! That’s the philosophy of life. But this blog ain’t about philosophy. This blog is based on one of the hottest topics in physics currently — time and space. Time. It is the most common yet the least understood concept. I mean, time is weird. If you start thinking about it deeply, you will get into a whirlpool of cofusions. It is there! And most of us have made peace with this fact.
But have you ever wondered whether ‘time’ is real? Is it? Or is it just a concoction of our brain? We certainly have a use for it, and it pretty much runs our lives on a daily basis. We constantly check the time, we make appointments based on it, we judge the courses of our lives based on the seeming fact that certain events happen to us at one point in time and not another. And as sure as it sounds we can never regain back the lost time.
But the big question which arises here is — “Do we really understand how time works?” Einstein showed at the beginning of 20th century that we don’t. Time doesn’t seem to work the same way throughout our universe.
A majority of physicists believe that the universe is expanding at an ever-accelerating rate. Before moving forward, let us study the term “rate”. Rate is defined as the change of a quantity with respect to time. While defining rate, we assume that time is independent of any other factor and moves at a constant speed. But some physicists believe that it may not be the case with the expansion of the universe.
“We do not say that the expansion of the universe itself is an illusion, what we say may be an illusion is the acceleration of this expansion — that is, the possibility that the expansion is, and has been, increasing its rate”, said Senovilla.
Confused, eh?
Let’s consider it mathematically. For simplicity, I will use layman terms in the equations.
rate =( Amount of expansion of the universe from time t1 to t2)/(t2-t1)
Now keeping the above equation in mind, let us think about how might the rate increase. Clearly, the rate will increase when the expansion of the universe increases i.e. the universe expands more with the passing time instant as compared to previous instant. But, for a moment let us assume that the numerator is constant i.e. the “amount” of expansion is constant for any two time intervals. Then, for the rate to increase, we should have a decreasing denominator i.e. the passage of time should not be a constant speed process anymore — THE TIME SHOULD SLOW DOWN.
Time might be slowing down, and that means that it could eventually stop altogether!
Now think about what it sounds like when an ambulance passes you on the street, sirens blazing. As it drives away from you, the siren begins to drop in pitch. This is Doppler effect, and it happens because sound waves ever so slightly stretch as the ambulance drives away from you, meaning they reach you at a slower rate (i.e. a lower frequency). But what if the laws of physics changed when that ambulance passed, and instead of its speed causing that drop in frequency, it was the passage of time?
If time were slowing down, that would also make sound waves reach you at a lower frequency. That’s essentially what Senovilla’s team is suggesting. We “know” the universe is expanding at an accelerating rate because galaxies further away from us have a greater redshift — light’s version of that ambulance Doppler effect- than galaxies closer to us, meaning they’re moving faster.
It was thought that supernovae at huge distances from the Earth were moving away faster from us than the things that were relatively nearby us, giving the impression that the universe is expanding. But what if this is not the case? Even String theory suggests that the supernovae are not actually moving away, but that time is actually slowing down, meaning that the light is taking longer to reach us.
String theory says that our universe exists on the surface of a membrane called a ‘brane’. Now you must be wondering what a ‘brane’ is? A brane is a physical object that generalizes the notion of a point particle to higher dimensions. Branes are dynamical objects which can propagate through space-time according to the rules of quantum mechanics. They have mass and can have other attributes such as charge.
A ‘brane’ exists in a hyperspace. All branes can have the different number of dimensions; ours happen to have three spatial dimensions and one-time dimension, but others could have no time dimension or multiple time dimensions. Dimensions in those other branes could even swing between different versions: space could become time and vice versa. That’s what the researchers think might be happening to our time dimension: It’s slowly turning into space dimension. If it succeeds, our universe would be frozen in time and exist in four-dimensional space.
We’d experience this as a gradual slowing of time-so gradual, in fact, that for the first billion years or so, we’d only see its evidence in grand scales like the movement of faraway galaxies. “Our calculation shows that we would think that the expansion of the universe is accelerating,” said Senovilla. “Any observation of dark energy could be evidence that our brane is changing significantly and the time is disappearing.”
But don’t worry! It won’t affect you in any way. The slowing down of time, if it actually exists, is so so gradual that it won’t have any effect on even thousand generations. For those of us who thought, we could actually save ourselves from the huge maths homework — better luck next “time”. But yeah, use your time wisely — even if it’s slowing down, that doesn’t make it less priceless an asset.
Stay Tuned for Future Blogs.
Cheers
Rohit Kumar
Team Technothlon 2018
